Female Cave Insects With Penises Have Sex for 40-70 Hours

In an excellent new discovery in Brazil, insects of the Neotrogla genus who live in caves have been discovered with completely role-reversed genitalia. The boss female has a penis and the male has a vagina, and they get after it for 40-70 hour stretches.

According to a study in Current Biology, this isn't the first female creature with a penis, but it is the only example where the "intromittent organ is also reversed."